Locating masses or tumors in human tissue is necessary for a biopsy of the suspicious mass and subsequent removal. Sometimes it is possible to locate a mass merely by touching the skin above and around the suspicious area. However, often the mass is too small to be noticed by hand or is located in fatty tissue that interferes with determining the precise location of the mass. A specific example of the latter case is the location of small breast masses or calcifications.
Typically, the precise location of these types of masses can only be determined by x-ray analysis, using specialized instrumentation prior to a surgical operation to locate the mass to be removed. Typically, a very thin needle is inserted into the breast down to the mass under x-ray control (mammography). Once it is determined by x-ray control that the tip of the needle is located at the mass site, the patient is transported to an operating room, where the surgeon creates an incision in the breast by following along the path of the inserted needle with a scalpel until reaching the mass. This method often involves a very long incision and increases the risk of post-operative infection.
An alternate method of creating an incision to gain access to or remove a breast mass is to study x-rays of the breast mass taken from various angles. Based upon experience and notional extrapolation of the views from different angles of the breast mass, an incision is made in an attempt to cut along the most direct path to the mass.
Several devices exist for localizing masses in human tissue. See, for example, U.S. Pat. Nos. 4,682,606 to DeCaprio, 3,890,970 to Gullen, and 3,598,119 to White.
The DeCaprio patent discloses a surgical needle which is inserted into a located mass and encircled by a cork screw device. The cork screw device is twisted around the mass until the tip of the worm of the screw is just beyond the furthest side of the mass. Thereafter, the handle of the cork screw device is withdrawn and a guiding extension rod is replaced to direct the surgeon to the depth of the mass in the patient's tissue. Then, a cutting instrument is inserted over the extension rod for removing the mass from the tissue.
The Gullen patent discloses a surgical cannula for delivery of paracervical anaesthesia. The cannula includes a catheter having a closed distal end with a perforated membrane. The distal end is firm and sharp enough to be inserted into body tissue to a predetermined depth, as limited by a stop member. A thin membranous ballooning portion is provided proximate the distal end of the catheter for expansion upon application of a fluid pressure within the catheter to lock the cannula in place in the tissue. The device is left in the tissue of the patient by the ballooning portion to provide periodic supply of fluid anaesthesia during a surgical procedure.
Similar to the patent to Gullen, the White patent discloses a medical instrument for use in gynecological procedures to allow the administration of a paracervical block, continuously or intermittently, with only a single placement. The device comprises an elongated hollow tube having an open distal end and receiving a needle for guiding the device into tissue. An inflatable bladder is provided near the distal end of the hollow tube for retaining the device in the tissue and minimizing trauma associated with the procedure.
The prior art devices discussed above provide a procedure for retaining a catheter type instrument in the tissue of a patient, but fail to provide a procedure for precisely identifying a mass within the tissue. Moreover, the prior art devices are of an insufficient size to accurately locate a mass within breast tissue prior to surgery.